In recent years, techniques for downloading and reproducing movies, music, and the like are generalized along with the development of the Internet. Servers that distribute content, such as movies and music, provide a large number of services for downloading the content to PCs, AV devices, cell phones, and portable devices through a network.
Forms of the content distribution services include sell-off type content selling that allows the user to permanently view the purchased content and rental selling that allows the user to view the downloaded content within a limited viewing time.
In the typical download-type rental selling, a content provider that supplies content operates a content server and a DRM server, and a content receiver of a viewer downloads encoded rental content from the content server and acquires a decryption key of the encoded content and viewing conditions of the content from the DRM server. The viewing conditions of the content include information of the viewing time limit for viewing the content, a duplication condition of content, and the like.
In the reproduction of the rental content, the content receiver references the viewing time limit designated by the DRM server to start reproducing the content if the viewing time limit is not over and deletes the content if the viewing time limit is over.
The content receiver writes out the rental content and the viewing time limit to an exchangeable medium, such as an SD card, in some cases. In that case, the reproduction terminal of the SD card inspects the viewing time limit of the content when the rental content is about to be reproduced or when the reproduction is finished and deletes the content if the viewing time limit is over. An example of this type of reproduction method of content with viewing time limit includes a method described in Japanese Patent Laid-Open No. 2004-227282.
FIG. 17 is a sequence diagram for a terminal that has downloaded content from a server to move the content to view the content in another terminal in conventional content downloading as described in Japanese Patent Laid-Open No. 2004-227282.
A downloading terminal 601 can view content by storing the content distributed from a server 600 and acquiring a viewing license of the content from the server 600.
To view the content in another viewing terminal 602, the content can be moved from the downloading terminal 601 to the viewing terminal 602. However, the server 600 manages the viewing license in association with the downloading terminal 601. Therefore, the viewing terminal 602 that is another terminal acquires the viewing license again from the server 600 to view the content in the viewing terminal 602.
Forms of providing the viewing license include a viewing license with viewing time limit for providing a reproduction permission condition of the target content by designating absolute date and time and a viewing license with viewing term in which absolute date and time is not designated when the license is provided and only a viewable period, such as 48 hours, is designated to determine the viewing time limit upon the initial viewing on the terminal.
If the content is provided with the viewing license with viewing term, the terminal that reproduces the content does not acquire the viewing license from the server 600 again. The terminal itself determines and sets, for example, the date and time after 48 hours from the start of the initial reproduction of the content as the viewing time limit of the content.
An example of a form of selling the rental content includes a form called pack selling. The pack selling is a form of renting, for example, all twelve episodes of drama as one content group, or as a package, to provide twelve episodes at a lower price than when the episodes are individually purchased.
In this case, the price of the service paid by the user to the service provider is low. Instead, the viewing time limits of the entire pack contents are usually unified. Specifically, the viewing time limits of all twelve contents are set to the same date and time when viewing of any one of the contents is started after the download of twelve contents.